1. Ventilator management of acute respiratory failure in a case of eosinophilicbronchopneumopathy

3. progressive dyspnea over last 12 hours

5. Initial intervention•ketamine/valium induction, intubation and manual ventilation via AMBU bag on 100% 02 Differential diagnosis•acute CHF •generalised pneumonia- bacterial, fungal, aspiration •ARDS- but no concurrent predisposers identified •lung lobe torsion •neoplasia •small airway disease ????? atypical presentation

6. Arterial blood gas Severe respiratory acidosis- partial metabolic compensation Significant hypercapnia- hallmark of hypoventilation A-a gradient= 453mmHg (normal <150 on 100% O2) Hypoventilation + venous admixture

8. Bronchoscopy Mucosal hyperemia and thickening Diffuse airway hemorrhage, suspected secondary to increased transmural pressure and mucosal capillary rupture during acute respiratory distress

9. Quantity of mucoid secretions at carina Exaggerated concentric airway closure during expiration

10. BAL cytology

13. Dynamic hyperinflation/ intrinsic PEEP predispositions Small airway inflammation/ secretions/ collapse High respiratory rate Short expiratory time Large I:E ratio Patient/ ventilator asynchrony and breath stacking

14. Effects of dynamic hyperinflation ↑ end expiratory volume ↓tidal volume, with tidal ventilation occurring near total lung capacity ↓venous return and compromised cardiac output-> hemodynamic collapse and arrest Inspiratory muscles placed at a mechanical disadvantage- inefficient force/length relationship Increased risk of barotrauma, non-cardiogenicedema, pneumothorax Increased pulmonary hypertension, increased RV load

15. Elevated V/Q ratio Areas of V/Q of 10-40 in acute small airway disease Normal V/Q=1.0

17. Acute tricuspid regurgitation

19. Decreasing inspiratory/expiratory ratio- prolong expiratory times

22. Additional therapies Pre-emptive pleural catheter in the face of high airway pressures and risk of alveolar rupture/ tension pneumothorax Continuous tracheal insufflation of O2 via catheter positioned at carina- increased deadspace washout of CO2 Sodium bicarbonate low 0.5mEq/kg dose

23. Respiratory acidosis- NaHCO3 ? Positives Protective against increased cerebral blood flow and ICP elevations associated with hypercapnic acidosis post anoxic brain injury May relieve severe pulmonary hypertension exacerbated by hypercapnic acidosis mediated pulmonary vasoconstriction Treats decreased contractility of cardiac and vascular muscle ?

24. Negatives Effectiveness depends on ability to eliminate CO2 May raise PaCO2 in the context of hypoventilation May correct arterial pH but worsen intracellular acidosis Removal of the acidosis-mediated protective effects of hypercapnia on the cardiovascular system Extracellular pH may not reflect intracellular

25. Effects of hypercapnic acidosis Augmentation of pulmonary hypoxic vasoconstriction, reducing shunt Increased lung compliance -surfactant Protective against pulmonary ischemia/ reperfusion injury Facilitation of O2 unloading to tissues via Bohr effect on Hb dissociation curve Elevated cardiac output mediated through endogenous catecholamine release, same effect reduces GFR and increases renal fluid retention Increased cerebral tissue, intestinal wall and renal PO2 Protective vs cell death in anoxic hepatocytes

26. Monitoring of ventilation PaO2/ FiO2 ratio <200 ARDS, <300 ALI Oxygen Index Pmean%O2 ------------------------- PaO2 normal <2.0 Dead space fraction VD/VT=(PaCO2-PECO2)/PaCO2 Rapid shallow index f/VT<105 without mechanical support via ET tube

27. Progression in ventilatory indices

28. Overview of eosinophilicbronchopneumopathy Aetiology uncertain, suspected hypersensitivity to aerosolized antigens Increased CD4+:CD8+ T cell ratio ↑MMP activity -> collagenolysis/proteolysis with airway destruction/remodeling ↑eosinophil specific chemokines Gender bias towards females

29. Average age at presentation 4-6 years (range 3mths-13yrs) Cough +/- nasal discharge Diagnosis on BALF cytology R/O heartworm dx R/O helminth trigger vsfenbendazole trial Oral/inhaled glucocorticoids- avoid abrupt discontinuation/ parenteral depots Start @ 1mg/kg prednisone bid and taper after one to 2 weeks

30. Outcome for Mr Magoo Successfully weaned from mechanical ventilation after 60 hours of support 48 hrs later Nasal O2 support d/c Pneumothorax resolved and pleural catheter removed Left forelimb lameness

31. Suprascapular neuropathy Marked atrophy supraspinatus + infraspinatus m. Radial n reflex and proprioception intact Weak withdrawal Suspected critical illness polyneuropathy

33. NM blockers??? Link now in question

34. cytokine release

35. eosinophiliamyalgiaGood prognosis

36. Questions?